What Kind Of Allergies Cause A Skin Rash And Itch?

I have a skin rash and I think it might be some kind of allergies, but I’m not sure which kind, can anyone help?

Is There Such A Food Allergy That Would Make You Itch All Over?

Has anybody ever heard of a food allergy that would make you itch? If so, what is it usually caused by? I think yesterday I might have eaten something (although I don’t know what) and I’ve been itching all over ever since.